Pencil leg construction for compasses



Sept. 13, 1938. DE CESARIS 2,130,072

PENCIL LEG CONSTRUCTION FOR COMPASSES Filed April 30, 1934 [72%572 for Patented Sept. 13, 1938 UNlTED STATES PATENT OFFICE PENCIL LEG CONSTRUCTION FOR COIVIPASSES 1 Claim.

My present invention relates to the construction of compasses, and has particular reference to clamping devices utilized for gripping a pencil in the compass leg.

The pencil clamping devices now provided on compasses have certain disadvantages, in that they either look a pencil in place by denting or otherwise marring the pencil, or else require a strong clamping pressure, whereby small children have difficulty in properly operating the clamp.

These disadvantageous features are particularly objectionable because the pencil must be periodically sharpened, the sharpening usually requiring removal of the pencil from the compass and reclamping.

It is the principal object of my invention to provide a clamping device that is easily operated without the exercise of too much force. Another object of my invention is to provide a clamp that firmly grips a pencil of any standard size, without marring the pencil in any way.

With the above and other objects and advantageous features in view, my invention consists of a novel arrangement of parts more fully disclosed in the detailed description following, in conjunction with the accompanying drawing, and more specifically defined in the claim appended thereto.

In the drawing,

Fig. 1 is a plan view of a pencil compass equipped with the novel pencil clamp;

Fig. 2 is a front elevation of the clamp portion;

Fig. 3 is a side elevation of the clamp portion;

Fig. 4 is a sectional view on the line 4-4 of Fig. 2, the parts being shown in unclamped relation;

Fig. 5 is a view similar to Fig. 4, the parts being shown in clamped relation.

I have devised a novel pencil clamp arrangement for compasses that is simple to operate and is effective in locking, without requiring more than a slight effort on the part of the user to either lock or unlock the pencil from the compass. The novel clamp includes a barrel through which the pencil is inserted, a hinged lock bar, and a cam lever which engages the lock bar to force the lock bar into clamping engagement with the pencil, thus providing a simple arrangement which will function with any size pencil and is easily operated. In-this arrangement the barrel need not be of resilient material. I have also devised modified arrangements, which utilize a cam element for pressing the sides of the barrel together, and which utilize a slide element instead of a cam lever to press a lock bar against the pencil.

These novel arrangements are described in the detailed description following, and illustrated in the drawing, in which the compass I0, see Fig. 1,

has the novel pencil clamp H, which is formed integral, or may be secured to, one leg of the compass. The clamp l I, see Figs. 2 to 5, includes a generally cylindrical barrel l2 which may be of rigid or resilient metal, the barrel preferably having cut out portions to provide spaced pencil contact areas, and having aligned pairs of hinge ears l3, l4 between the spaced barrel sides l5, I6 which are pierced to receive the corresponding pintles of a cam lever I1 and a curved lock base I8. The cam lever has a cam end l9 engageable with the free end of the lock bar, and a lever portion 20 terminating in a finger engageable end 2| which normally rests between the ears l4 when the cam lever is in closed position. Both the cam lever and the curved lock bar are preferably stamped from sheet metal.

The operation of the novel clamp is now clear; a pencil of any standard size, round, hexagonal, or the like, is inserted through the barrel, the cam lever being in open position. The curved lock bar contacts the pencil side, due to its curvature; closing the cam lever forces the free end of the lock bar down, whereby the pencil is firmly gripped. The cam lever is readily opened by inserting a finger nail under the end 2 I.

The above described clamp does not require any resilience pf the barrel; if desired, however, the barrel may be resilient.

It is thus evident that the novel clamp is of simple structure, readily manufactured at low cost, and is easily operated, to both clamp and unclamp a pencil.

While I have described specific constructional embodiments of my invention, it is obvious that desired changes in the size, material, and arrangement of the parts and in their relative positioning and functioning, may be made to suit the requirements for different compass designs, Within the spirit and the scope of the invention as defined in the appended claim.

I claim:

A pencil leg for a compass or the like, comprising a pencil receiving part having a pencil clamp including a generally circular body portion with integral spaced parallel end walls, an arcuate member of sheet metal having a convex portion extending inwardly and hinged in said end Walls adjacent one end thereof and movable between said end walls to overlie an inserted pencil, and a cam lever hinged in the end Walls adjacent the other end thereof and having a cam element engageable with the free end of said member for forcing said member into locking engagement with the pencil, said cam lever overlying said member when in member engaging position.

FREDERICK DE CESARIS. 

